Yes, oftentimes it is very reliable but not always so double check to see how competitive the keyword really is. You can have a look at the top 10 pages on Google and use the Moz toolbar to see how strong the competition is. See if the competing pages use your keyword in their titles or URLs and things like that before you decide if it is accurate or not and check their backlinks.
Our metric is widely considered the most accurate one. Keyword Difficulty doesn't take into account any on-page factors. Keyword Difficulty evaluates the chances of getting into top 10 of search results
SEMrush or Moz are the most reliable tools for the purpose of Keyword Research depending upon the wide variety of data and credible information.
SEMrush is the most reliable tool for the purpose of keyword research. You can use it for your keyword research business.